Merge git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild
[linux-2.6] / drivers / s390 / char / tape_block.c
1 /*
2  *  drivers/s390/char/tape_block.c
3  *    block device frontend for tape device driver
4  *
5  *  S390 and zSeries version
6  *    Copyright (C) 2001,2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
7  *    Author(s): Carsten Otte <cotte@de.ibm.com>
8  *               Tuan Ngo-Anh <ngoanh@de.ibm.com>
9  *               Martin Schwidefsky <schwidefsky@de.ibm.com>
10  *               Stefan Bader <shbader@de.ibm.com>
11  */
12
13 #include <linux/fs.h>
14 #include <linux/module.h>
15 #include <linux/blkdev.h>
16 #include <linux/interrupt.h>
17 #include <linux/buffer_head.h>
18
19 #include <asm/debug.h>
20
21 #define TAPE_DBF_AREA   tape_core_dbf
22
23 #include "tape.h"
24
25 #define PRINTK_HEADER "TAPE_BLOCK: "
26
27 #define TAPEBLOCK_MAX_SEC       100
28 #define TAPEBLOCK_MIN_REQUEUE   3
29
30 /*
31  * 2003/11/25  Stefan Bader <shbader@de.ibm.com>
32  *
33  * In 2.5/2.6 the block device request function is very likely to be called
34  * with disabled interrupts (e.g. generic_unplug_device). So the driver can't
35  * just call any function that tries to allocate CCW requests from that con-
36  * text since it might sleep. There are two choices to work around this:
37  *      a) do not allocate with kmalloc but use its own memory pool
38  *      b) take requests from the queue outside that context, knowing that
39  *         allocation might sleep
40  */
41
42 /*
43  * file operation structure for tape block frontend
44  */
45 static int tapeblock_open(struct inode *, struct file *);
46 static int tapeblock_release(struct inode *, struct file *);
47 static int tapeblock_ioctl(struct inode *, struct file *, unsigned int,
48                                 unsigned long);
49 static int tapeblock_medium_changed(struct gendisk *);
50 static int tapeblock_revalidate_disk(struct gendisk *);
51
52 static struct block_device_operations tapeblock_fops = {
53         .owner           = THIS_MODULE,
54         .open            = tapeblock_open,
55         .release         = tapeblock_release,
56         .ioctl           = tapeblock_ioctl,
57         .media_changed   = tapeblock_medium_changed,
58         .revalidate_disk = tapeblock_revalidate_disk,
59 };
60
61 static int tapeblock_major = 0;
62
63 static void
64 tapeblock_trigger_requeue(struct tape_device *device)
65 {
66         /* Protect against rescheduling. */
67         if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
68                 return;
69         schedule_work(&device->blk_data.requeue_task);
70 }
71
72 /*
73  * Post finished request.
74  */
75 static inline void
76 tapeblock_end_request(struct request *req, int uptodate)
77 {
78         if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
79                 BUG();
80         end_that_request_last(req, uptodate);
81 }
82
83 static void
84 __tapeblock_end_request(struct tape_request *ccw_req, void *data)
85 {
86         struct tape_device *device;
87         struct request *req;
88
89         DBF_LH(6, "__tapeblock_end_request()\n");
90
91         device = ccw_req->device;
92         req = (struct request *) data;
93         tapeblock_end_request(req, ccw_req->rc == 0);
94         if (ccw_req->rc == 0)
95                 /* Update position. */
96                 device->blk_data.block_position =
97                         (req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
98         else
99                 /* We lost the position information due to an error. */
100                 device->blk_data.block_position = -1;
101         device->discipline->free_bread(ccw_req);
102         if (!list_empty(&device->req_queue) ||
103             elv_next_request(device->blk_data.request_queue))
104                 tapeblock_trigger_requeue(device);
105 }
106
107 /*
108  * Feed the tape device CCW queue with requests supplied in a list.
109  */
110 static inline int
111 tapeblock_start_request(struct tape_device *device, struct request *req)
112 {
113         struct tape_request *   ccw_req;
114         int                     rc;
115
116         DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
117
118         ccw_req = device->discipline->bread(device, req);
119         if (IS_ERR(ccw_req)) {
120                 DBF_EVENT(1, "TBLOCK: bread failed\n");
121                 tapeblock_end_request(req, 0);
122                 return PTR_ERR(ccw_req);
123         }
124         ccw_req->callback = __tapeblock_end_request;
125         ccw_req->callback_data = (void *) req;
126         ccw_req->retries = TAPEBLOCK_RETRIES;
127
128         rc = tape_do_io_async(device, ccw_req);
129         if (rc) {
130                 /*
131                  * Start/enqueueing failed. No retries in
132                  * this case.
133                  */
134                 tapeblock_end_request(req, 0);
135                 device->discipline->free_bread(ccw_req);
136         }
137
138         return rc;
139 }
140
141 /*
142  * Move requests from the block device request queue to the tape device ccw
143  * queue.
144  */
145 static void
146 tapeblock_requeue(void *data) {
147         struct tape_device *    device;
148         request_queue_t *       queue;
149         int                     nr_queued;
150         struct request *        req;
151         struct list_head *      l;
152         int                     rc;
153
154         device = (struct tape_device *) data;
155         if (!device)
156                 return;
157
158         spin_lock_irq(get_ccwdev_lock(device->cdev));
159         queue  = device->blk_data.request_queue;
160
161         /* Count number of requests on ccw queue. */
162         nr_queued = 0;
163         list_for_each(l, &device->req_queue)
164                 nr_queued++;
165         spin_unlock(get_ccwdev_lock(device->cdev));
166
167         spin_lock(&device->blk_data.request_queue_lock);
168         while (
169                 !blk_queue_plugged(queue) &&
170                 elv_next_request(queue)   &&
171                 nr_queued < TAPEBLOCK_MIN_REQUEUE
172         ) {
173                 req = elv_next_request(queue);
174                 if (rq_data_dir(req) == WRITE) {
175                         DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
176                         blkdev_dequeue_request(req);
177                         tapeblock_end_request(req, 0);
178                         continue;
179                 }
180                 spin_unlock_irq(&device->blk_data.request_queue_lock);
181                 rc = tapeblock_start_request(device, req);
182                 spin_lock_irq(&device->blk_data.request_queue_lock);
183                 blkdev_dequeue_request(req);
184                 nr_queued++;
185         }
186         spin_unlock_irq(&device->blk_data.request_queue_lock);
187         atomic_set(&device->blk_data.requeue_scheduled, 0);
188 }
189
190 /*
191  * Tape request queue function. Called from ll_rw_blk.c
192  */
193 static void
194 tapeblock_request_fn(request_queue_t *queue)
195 {
196         struct tape_device *device;
197
198         device = (struct tape_device *) queue->queuedata;
199         DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
200         BUG_ON(device == NULL);
201         tapeblock_trigger_requeue(device);
202 }
203
204 /*
205  * This function is called for every new tapedevice
206  */
207 int
208 tapeblock_setup_device(struct tape_device * device)
209 {
210         struct tape_blk_data *  blkdat;
211         struct gendisk *        disk;
212         int                     rc;
213
214         blkdat = &device->blk_data;
215         spin_lock_init(&blkdat->request_queue_lock);
216         atomic_set(&blkdat->requeue_scheduled, 0);
217
218         blkdat->request_queue = blk_init_queue(
219                 tapeblock_request_fn,
220                 &blkdat->request_queue_lock
221         );
222         if (!blkdat->request_queue)
223                 return -ENOMEM;
224
225         elevator_exit(blkdat->request_queue->elevator);
226         rc = elevator_init(blkdat->request_queue, "noop");
227         if (rc)
228                 goto cleanup_queue;
229
230         blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
231         blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
232         blk_queue_max_phys_segments(blkdat->request_queue, -1L);
233         blk_queue_max_hw_segments(blkdat->request_queue, -1L);
234         blk_queue_max_segment_size(blkdat->request_queue, -1L);
235         blk_queue_segment_boundary(blkdat->request_queue, -1L);
236
237         disk = alloc_disk(1);
238         if (!disk) {
239                 rc = -ENOMEM;
240                 goto cleanup_queue;
241         }
242
243         disk->major = tapeblock_major;
244         disk->first_minor = device->first_minor;
245         disk->fops = &tapeblock_fops;
246         disk->private_data = tape_get_device_reference(device);
247         disk->queue = blkdat->request_queue;
248         set_capacity(disk, 0);
249         sprintf(disk->disk_name, "btibm%d",
250                 device->first_minor / TAPE_MINORS_PER_DEV);
251
252         blkdat->disk = disk;
253         blkdat->medium_changed = 1;
254         blkdat->request_queue->queuedata = tape_get_device_reference(device);
255
256         add_disk(disk);
257
258         INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
259                 tape_get_device_reference(device));
260
261         return 0;
262
263 cleanup_queue:
264         blk_cleanup_queue(blkdat->request_queue);
265         blkdat->request_queue = NULL;
266
267         return rc;
268 }
269
270 void
271 tapeblock_cleanup_device(struct tape_device *device)
272 {
273         flush_scheduled_work();
274         device->blk_data.requeue_task.data = tape_put_device(device);
275
276         if (!device->blk_data.disk) {
277                 PRINT_ERR("(%s): No gendisk to clean up!\n",
278                         device->cdev->dev.bus_id);
279                 goto cleanup_queue;
280         }
281
282         del_gendisk(device->blk_data.disk);
283         device->blk_data.disk->private_data =
284                 tape_put_device(device->blk_data.disk->private_data);
285         put_disk(device->blk_data.disk);
286
287         device->blk_data.disk = NULL;
288 cleanup_queue:
289         device->blk_data.request_queue->queuedata = tape_put_device(device);
290
291         blk_cleanup_queue(device->blk_data.request_queue);
292         device->blk_data.request_queue = NULL;
293 }
294
295 /*
296  * Detect number of blocks of the tape.
297  * FIXME: can we extent this to detect the blocks size as well ?
298  */
299 static int
300 tapeblock_revalidate_disk(struct gendisk *disk)
301 {
302         struct tape_device *    device;
303         unsigned int            nr_of_blks;
304         int                     rc;
305
306         device = (struct tape_device *) disk->private_data;
307         BUG_ON(!device);
308
309         if (!device->blk_data.medium_changed)
310                 return 0;
311
312         PRINT_INFO("Detecting media size...\n");
313         rc = tape_mtop(device, MTFSFM, 1);
314         if (rc)
315                 return rc;
316
317         rc = tape_mtop(device, MTTELL, 1);
318         if (rc < 0)
319                 return rc;
320
321         DBF_LH(3, "Image file ends at %d\n", rc);
322         nr_of_blks = rc;
323
324         /* This will fail for the first file. Catch the error by checking the
325          * position. */
326         tape_mtop(device, MTBSF, 1);
327
328         rc = tape_mtop(device, MTTELL, 1);
329         if (rc < 0)
330                 return rc;
331
332         if (rc > nr_of_blks)
333                 return -EINVAL;
334
335         DBF_LH(3, "Image file starts at %d\n", rc);
336         device->bof = rc;
337         nr_of_blks -= rc;
338
339         PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
340         set_capacity(device->blk_data.disk,
341                 nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
342
343         device->blk_data.block_position = 0;
344         device->blk_data.medium_changed = 0;
345         return 0;
346 }
347
348 static int
349 tapeblock_medium_changed(struct gendisk *disk)
350 {
351         struct tape_device *device;
352
353         device = (struct tape_device *) disk->private_data;
354         DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
355                 device, device->blk_data.medium_changed);
356
357         return device->blk_data.medium_changed;
358 }
359
360 /*
361  * Block frontend tape device open function.
362  */
363 static int
364 tapeblock_open(struct inode *inode, struct file *filp)
365 {
366         struct gendisk *        disk;
367         struct tape_device *    device;
368         int                     rc;
369
370         disk   = inode->i_bdev->bd_disk;
371         device = tape_get_device_reference(disk->private_data);
372
373         if (device->required_tapemarks) {
374                 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
375                 PRINT_ERR("TBLOCK: Refusing to open tape with missing"
376                         " end of file marks.\n");
377                 rc = -EPERM;
378                 goto put_device;
379         }
380
381         rc = tape_open(device);
382         if (rc)
383                 goto put_device;
384
385         rc = tapeblock_revalidate_disk(disk);
386         if (rc)
387                 goto release;
388
389         /*
390          * Note: The reference to <device> is hold until the release function
391          *       is called.
392          */
393         tape_state_set(device, TS_BLKUSE);
394         return 0;
395
396 release:
397         tape_release(device);
398  put_device:
399         tape_put_device(device);
400         return rc;
401 }
402
403 /*
404  * Block frontend tape device release function.
405  *
406  * Note: One reference to the tape device was made by the open function. So
407  *       we just get the pointer here and release the reference.
408  */
409 static int
410 tapeblock_release(struct inode *inode, struct file *filp)
411 {
412         struct gendisk *disk = inode->i_bdev->bd_disk;
413         struct tape_device *device = disk->private_data;
414
415         tape_state_set(device, TS_IN_USE);
416         tape_release(device);
417         tape_put_device(device);
418
419         return 0;
420 }
421
422 /*
423  * Support of some generic block device IOCTLs.
424  */
425 static int
426 tapeblock_ioctl(
427         struct inode *          inode,
428         struct file *           file,
429         unsigned int            command,
430         unsigned long           arg
431 ) {
432         int rc;
433         int minor;
434         struct gendisk *disk;
435         struct tape_device *device;
436
437         rc     = 0;
438         disk   = inode->i_bdev->bd_disk;
439         BUG_ON(!disk);
440         device = disk->private_data;
441         BUG_ON(!device);
442         minor  = iminor(inode);
443
444         DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
445         DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
446
447         switch (command) {
448                 /* Refuse some IOCTL calls without complaining (mount). */
449                 case 0x5310:            /* CDROMMULTISESSION */
450                         rc = -EINVAL;
451                         break;
452                 default:
453                         PRINT_WARN("invalid ioctl 0x%x\n", command);
454                         rc = -EINVAL;
455         }
456
457         return rc;
458 }
459
460 /*
461  * Initialize block device frontend.
462  */
463 int
464 tapeblock_init(void)
465 {
466         int rc;
467
468         /* Register the tape major number to the kernel */
469         rc = register_blkdev(tapeblock_major, "tBLK");
470         if (rc < 0)
471                 return rc;
472
473         if (tapeblock_major == 0)
474                 tapeblock_major = rc;
475         PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
476         return 0;
477 }
478
479 /*
480  * Deregister major for block device frontend
481  */
482 void
483 tapeblock_exit(void)
484 {
485         unregister_blkdev(tapeblock_major, "tBLK");
486 }